Method of treating sheets of vulcanizable plastics.



R. B. PRICE.

METHOD OF TREATING SHEETS 0F VULCANIZABLE PLASTICS. APPLICATION mu) APR.29. 1915. nznzwzn mu 7. I916- l,21 1,487. Patented Jan. 9. 1917.

$51 M0 Ga 21 ymwrwvwazmz UNITED STATES PATENT OFFICE.

RAYMOND B. PRICE, OF NEW YORK, N. Y., ASSIGNOR T0 RUBBER REGENERATINGCOMPANY, A CORPORATION OF INDIANA.

METHOD OF TREATING SHEETS OF VULCANIZABLE PLASTICS.

Application filed April 29, 19l5, Serial No. 24.756.

To all whom it may con ern lle it known that I, RAYMOND ll. lmt'i-z. acitizen of the linited States, residing in the city, county and State ofNew York, have invented certain new and useful lm provements in.\lethods ol 'lreating Sheets of l'uleunizahle Plastics. of which thefollowing is a full. clear. and exact description My invention relatesto a method of treatin shected \ul anizable plastics and moreparticularly to a treatment thereof preparatory to subjecting thematerial to the a tion of a rnlcanizint medium.

In preparing sheeted vuhranizable plastic for yulr'anization. thesuperficial area as compared with the mas of the material; theflexibility ol' the material: and the conditions attendant upon theformation of a plurality ot plies ot' the sheeted material in- (-identalto the convenient handling and 'ulcanizing thereof, result in a tendencyto trap air and other gases or sometimes volutile. fluids betweensucceeding plies or within the plies themselves. When the product soughtis vulcanized sheets of the plastic. this condition results in thelikelihood of superficial blemishes on the sheets. ll' how ever, it; bedesired to combine a plurality of layers of the material into a solidmass or block of material, it is likely there will be concealed pocketsin the mass thu formed, or blisters upon the surface thereof.

By my present invention, 1 am enabled to prepare sheeted vulcanizableplastic for vulcanization in a manner to obviate the presence ofentrapped fluids betwern adjacent layers in the body of a mass otmaterial formed by a plurality of such layers and from the sheetsthemselves. In securing these results, the air, gas or other lluidspresent between succeeding sheets or layers by reason of the manner ofdisposing one layer upon another, either in contact or with a separatingmedium is removed prior to vulcanization as are also the fluids that mayhave been entrapped in the material itself. Any fluid imprisoned in thebody of the material, as well as the fluid entrapped between the layersis also removed either wholly, or in such a degree as to result in aproduct substantially freefrom material defects resulting from thepresence of the fluids during vulcanization thereby obtain-Specification of Letters Patent.

Patented Jan. 9, 1917.

Renewed July 7, 1916. Serial No. 107,973.

ing a solid homogeneous mass. Subseouently to the withdrawal of thesetluitls, the :u.- -umulation ol layers are compacted with a resultantclosure of any voids or poeli'ets rcsultin; from the withdrawal ol' thelluids, thereby imparting a substantially unil'orm density to the heetedplastic.

The in\entiou consists primarily in the method of treating sbe tcd\ulcunizul)l( plastic con isting in superimposing or plying up aplurality of layers of vulcanizable plastic oJnupon another. and\vitlulrawing lluids from between said sheets or layers by subje tingthem to a reduced lluid pressure, and to a nu-chanical pres ure, thelatter beinp, applied for any desired period previous to, eom-urrcntlvwith. or subsequently to the application (it the reduced fluid pressure.or the nu-chanical pressure may be applied during two or eren all threeof these periods as may be found necessary in any particular instance toproduce the desired results. and in such other novel steps as arehereinafter set l orth and described aml more particularly pointed outin the claims hereto appended.

In the accompauving drawings, l have. illustrated two aspects ol' myinvention. one wherein the product sought is separable sheets ol'material prcpurcd l'or vulcanizu tion as sheets. and the other whereinthe product is a Mllltl homogeneous mass ol'1n:lterial prepared forvulcanization.

.In the drawings: Figure l is a view of a hydraulic press and itsappurtenam-es, which may be used in t lltdtl'tl 'llt'C of my invention,separable sheets being shown under treatment thereby, aml Fig. :2 is aview of the press table and head, sheets to be compawted in ahpmogeneous mass being shown under treatment thereby.

liilv'e. letters refer to like parts in both of said views.

Referring to the drawings, 1 indicates the cylinder, 2 the piston and tthe main frame of the press. The piston 2 supports the usual tablelwithin a chamber Uppositely disposed to said table is a head (3 carriedby the top 7 for the chamber 5. Comnnmicating with the chamber 5 is oneor more conduits 8 connected with a'suction pump or other pressurecontrolling meclianism (not shown) Vv'hile the foregoing mechanism formsno Htl ll t) part of my invention it is adapted for use in the practiceof my invention, and my improved method will be described in connec tionwith this particular mechaiiism, it being understood that the inventionis not limited to the use of any particular mechanism. For instance. inead' ol' piling the sheets as here shown they might be rolled in a coilor instead of ceiling separate sheets, a single long sheet may befornn-d and then coiled. and the coil may be subjected to a compactingpressure by any preferred or well known mea s instead of the press hereshown.

\Vlu-n it is desired to produce separable sheets of vulcanizable plasticfor vulcanization, a plurality of sheets 1) are superimposed one uponanother, separated by sheets 10 of tin-foil, or other suitable materialwhich will have the etl'ect oi preventing the adhesion of succeedingsheets tocach other. in the drawings, the sheets J are shown as laidperfe tly llat, in a pile on the table 4. and alternated with andseparated by the strata of sepi-trating medium it). The pressure withinthe chamber 3 is then reduced, the lowering of the pressure. or thepresence of a vacuum or partial vacuum about the pile, resulting in theremoval of any air, gases or other lluids trapped between the sheets andthe separating medium, or within the body oi any sheet. If desired. thechamber may be heated as for instance by supplying heat to the table -l'and head I) to accelerate the action resulting from the low pressurewithin the chamber 5. 'heu heat is used, however, where the rubber hascompounded with it the sulfur necessary for vulcanization, it should beat a te1upe.-'-iture below the vulcanizing point. The withdrawal of thelluids from between succeeding layers of the pile, will have a tendencyto cause a settling of the pile. The reduced pressure about the pile ismaintained for a suliicientperiod to remove. substantially all of theair, gases, or other fluids between or within the sheets. Thereafter,the pile is compressed under pressure through the'admission of fluid tothe cylinder 1, ,while maintaining the reduced pressure surrounding it,thus eompactim the pile in its entirety as well as the sheets of plasticcontained therein. This pressure will bring adjoining sheets of thepile, whether of plustic material or of a separating medium, lIltO suchintimate contact as to close all 'voids and prevent the entrance of airor other uses therebctween or within the material, when the low pressurein the chamber 5 is relieved.

When practising the invention in the manner illustrated in Fig. 2 aplurality of sheets of vulcanizable plastic are piled one upon anotherin surface contact with each other. T subjection of the pile so formed,first to a, educed pressure about the pile,

and second to compression while maintaining this reduced pressurethereabout will have the same etiect as heretofore described, exceptthat in the absence of a separating medium between succeeding sheets ofthe plastic, the product instead of being a pile of separable sheets,will be a solid, homogeneous mass of the plastic frde from entrappedair, gases, or other fiui ls.

The compression of the pile in either instance referred to, will have heeffect of sealing the edges of the pile-in a manner to prevent theentrance of air or other gases to replace those withdrawn during thatinterval when the pile is subjected to are due-ed pressurel Rubber stockmade according to my invention is ordinarily intended to be subsequently given its final shape and then vulcanized. It is feasiblehowever, when desired, to vulcanize the sheets or mass of rubber,duringor subsequent to the application of the reduced pressure, directlywithin the apparatus employed for preparing the rubber. In such a casemeans are afl'orded for supplying the required degree of heat to thechamber containing the goods, which may be attained by any well-known orpreferred manner.

llaving described my invention what I 95 claim as new and desire to haveprotected by Letters Patent is:

l. The method of treating sheets of vulcanizable plastic consisting insuperimposing a plurality of sheets of vulcanizable 10o plastic one uponanother: and thereafter withdrawing fluids from within and between saidsheets by subjecting the pile to a reduced )ressure.

T18 method of treating sheets of vul- 105 canizable plastic consistingin su erimposing a plurality of sheets of vu canizable plastic one uponanother, thereafter withdrawing fluids from within and between saidsheets by subjecting the pile to a reduced 110 pressure and finallycompressing the pile.

3. The method of treating sheets of vuleauizable plastic consisting insuperimposing a. plurality of sheets of vulcanizable )lilStlC one uponanother, thereafter subject- 115 mg the pile to the action of heatinsuliicient to vnlcanize said plastic, and simultaneously therewith orsubsequently thereto withdrawing fluids from within and between saidsheets by subjecting the pile to a reduced 1 20 pressure. t

4. The method of treating sheets of vulcanizable plastic consisting inan erimposing a plurality of sheets of vucanizable plastic one uponanother, thereafter subjectduced pressure and finally compressing thepile while subjecting it to the reduced pressures 5. The method oftreating sheets of vulcanizable plastic consisting in superimpos ing aplurality of alternately arranged sheets if vulcanizable plastic andstrata of a non-vu lcanizable separating medium, and withdrawing fluidsfrom within said sheets and from between them and said separating strataby subjecting the pile to a reduced pressure.

(3. The method of treating sheets of vul- -anizable plastic consistingin superimposing a plurality of alternately arranged sheets of avulcanizable plastic and strata of a nonvulcanizable separating medium,withihzuv ing fluids from within said sheets and from between them andsaid se )ara'ting strata by subjecting the pile to a ret uced pressureand compressing the pile while subjecting it to a reduced pressure.

'7. The method of treating sheets of Yllleanizable plastic consisting insuperimposing a plurality of alternately arranged sheets of vuleanizableplastic and strata of a nonrulcanizable separating medium, subjectingthe pile to the action of heat insullicient to vulcanize the plastic andwithdrawing the fluids from within said sheets and from between them andsaid separating strata by subjecting the pile to a reduced pressure.

8. The method of treating sheets of vulcanizable plastic consisting insuperimposing a plurality of alternately arranged sheets of vulcanizableplastic and strata of a nonvnleanizable separating medium, subjectingthe pile to the action of heat insutlieient to vnlcanize the plastic,withdrawing the fluids from within said sheets and from between them andsaid separating strata by subjecting the pile to a reduced pressure, andcompressing the pile while subjecting it to a reduced pressure.

9. The method of treating sheets of vulcanizable plastic consisting informing a pile of alternately arranged flat sheets ofyulcanizableplastic and strata of a non-vulcanizable separating medium, reducing thepres sure about said pile whereby the fluids will be withdrawntherefrom. and thereafter compressing said pile to close the voidsresulting from the withdrawal of said fluids.

10. The method of treating sheets of vulcanizable plastic consisting insuperimposing a plurality of sheets of Vnlcanizable plastic one uponanother, thereafter subecting said sheets to the action of a reducedpressure until the fluids from within and between said sheets aresubstantially removed, and before said reduced pressure is disc0n tinnedsubjecting the pile to a compacting pressure.

Signed at New York, N. Y., this 27th day of April, 1915.

RAYMOND B. PRICE.

